Implementation of emerging technologies for NOx reductions

Abstract:

Paper presented at the 6th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 30 June - 2 July, 2008.

The U. S. manufacturing sector uses more
energy for steam generation than for any
other single purpose. In 2002, steam
accounted for 31% of total U. S.
manufacturing energy consumption. This
high-energy demand in part reflects the
reliance on an aging U. S. industrial boiler
population employing designs that
conceptually vary little from those used at
the end of the 19th century. As such, new
developments are limited and have offered
only incremental gains in operational
efficiency. The U. S. manufacturing sector
utilizes more than 33,000 boilers with
capacities greater than 10 million Btu/hr. Of
these, more than 80% were purchased prior
to 1978, with the largest share purchased in
the 1960’s. However, an important window
of opportunity to reduce steam generation
energy use will open to U. S. manufacturers
as they begin to replace their aging stock of
existing industrial boilers nearing
retirement.
Researchers are working to develop new,
breakthrough steam generation technologies
that could potentially save U. S. industry
billions of dollars per year in operating costs
and substantially lower associated
environmental impacts. By utilizing a
unique boiler geometry incorporating a twostage
fire tube design and heat recovery
system that are both compact and highly
efficient (>94% HHV efficiency), First
Generation Super Boilers will offer up to
25% increases in steam generation
efficiency and occupy substantially reduced
footprints relative to their conventional
counterparts. Efficiency gains alone could
result in total U. S. manufacturing energy
cost savings of approximately $6 billion per
year. Reduced footprints also enable new
opportunities for boiler modularization. In
addition, the First Generation Super
Boilers will integrate several novel
technologies to achieve extraordinarily
low emissions NO<5 ppmv, aiding in
compliance with the stringent emissions
regulations.
During the past three decades, several
research efforts have been directed to find
solutions for NOx reductions. The major
NOx emission sources are from vehicles and
industrial boilers. Power plant smokestacks
are a significant source of dangerous
pollutants, including nitrogen oxides (NOx),
sulfur dioxide (SO2), and sooty particles
that cause unhealthy ozone and particulate
pollution in communities across the nations.
Industrial boilers account for 25% of NOx
that is emitted worldwide. National
emission of NOx over past few years has
increased by about 20% whereas all other
pollutants have decreased since the
implementation of Clean Air Act of 1970
which is a United States Federal law that
requires the Environmental Protection
Agency (EPA) to develop and enforce
regulations to protect the general public
from exposure to airborne pollutants that are
known to be hazardous to human health.
The Industrial Technologies Program (ITP)
of the U. S. Department of Energy (DOE)
has developed several energy efficient
programs such as Best Practices Tools and
Energy Efficient Technologies including
NOx and Energy Assessment Tools, which
help manufacturers to implement, assess and
analyze NOx emissions, and energy
efficiency improvements. With the help of
these tools we can compare how various
technology applications and efficiency
measures affect overall costs and reduction
of NOx and also select the best method for
reducing NOx in a system.
In this paper, an application of NOx and
Energy assessment tools to a natural gas
boiler is discussed. NOx reduction analysis
using current generation low NOx burner,
Next generation ultra NOx burner, and
Selective catalytic reduction is performed
and results are compared. The details of the
application to NxEAT and its advantages
like reduction of NOx emissions in the
environment are discussed.